Stalingrad class battlecruiser
The Stalingrad class battlecruiser, also known in the Soviet Union as Project 82 (Russian: Тяжёлые крейсера проекта 82), was intended to be built for the Soviet Navy after World War II. Four ships were ordered and completed in the early 1950s. A heavy cruiser was designed before the Second World War as an intermediate between the Kirov class cruiser and Chapayev class cruiser and the Kronshtadt class battlecruiser. The specification, or OTZ in Russian, was issued in May 1941, but plans were shelved with the invasion of the Soviet Union by Nazi Germany. Construction was proposed again in 1943. After a lengthy design period, which Premier Joseph Stalin—a major supporter of the project—often had a hand in, keels for two ships were laid at the Nikolayev South Shipyard in Nikolayev, Ukrainian Soviet Socialist Republic, Soviet Union (1951) and the Baltic Works in Leningrad (1952) and two ships was planned for the shipyard in Severodvinsk, Russian Soviet Federative Socialist Republic, Soviet Union. The Project 82 design which was ordered would have been much larger than the original intermediate design, so much so that they were considered the successors to the Kronshtadt class battlecruiser, which had been completed at the outbreak of World War II. As envisioned by Stalin, the Stalingrad battlecruisers' role would be to disrupt and break up an enemy's light cruisers when they approached the Soviet coast. The Stalingrad class battlecruisers together with the Kirov class battlecruisers are the largest battlecruisers ever built for the Soviet Union and the largest battlecruisers ever built in the world. Background and genesis The roots of the Project 82-class began back in May 1941 when the Main Naval Staff approved tactical requirements (Russian: Operativno Takticheskoye Zadanie) for a medium-sized cruiser between the light cruisers of the Kirov class cruisers and Chapayev class cruisers and the "heavy cruisers" of the Kronshtadt class battlecruisers in size. It was intended to fulfill the following roles: *Engage enemy cruisers armed with 203 mm (8.0 in) guns *Destroy enemy light cruisers *Support its own light cruisers *Lay minefields *Suppress the enemy's medium-caliber coast defense batteries and support landing operations *Conduct operations against the enemy's maritime lines of communication To accomplish these missions the Navy expected a ship of 20,000 tonnes (20,000 long tons) or smaller, armed with eight 203-millimeter (8.0 in) and twelve 100-millimeter (3.9 in) guns, twelve 37-millimeter (1.5 in) anti-aircraft guns and one triple 533-millimeter (21.0 in) torpedo mount. It was to be armored to withstand 203 mm shells with a speed not less than 36 knots (41 mph; 67 km/h), a range of 10,000 nmi (18,520 km) at 20 knots (23 mph; 37 km/h) and able to carry four seaplanes launched by two catapults. Three preliminary designs were proposed in response, but only one, which displaced 25,000 tonnes (25,000 long tons), was able to meet all of the requirements. However, the designers recommended an increase in the main armament caliber to 220 millimeters (8.7 in), a strengthened anti-aircraft battery and reductions in the armor protection, speed, and range, but the start of Operation Barbarossa a month later rendered these plans moot. The project was revived in 1943 with a new requirement issued on 15 September. This was basically identical to the original, but added one new requirement: "Protect the operations of aircraft carriers and conduct joint operations with them." Estimated characteristics were a displacement between 20,000–22,000 tonnes (20,000–22,000 long tons), nine main guns between 210–230 mm (8.3–9.1 in), a secondary battery of a dozen 130-mm dual-purpose guns and thirty-two 37-mm AA guns. The speed, range and aircraft requirements remained the same, although the torpedo tubes were dropped. Over a dozen preliminary designs had been proposed by May 1944, but none were acceptable. A new tactical requirement was issued in November 1944 that envisioned a more realistic displacement of 25,000–26,000 tonnes (25,000–26,000 long tons) while the speed was dropped to 33 knots (38 mph; 61 km/h) and the range to 8,000 nmi (14,820 km). Armament was also revised to nine 220-mm guns, sixteen 130-mm guns, thirty-two 45-millimeter (1.8 in) and twenty 23-millimeter (0.91 in) AA guns. These last guns were changed to 25 mm (0.98 in) in 1945. Admiral Nikolai Kuznetsov believed that these ships could protect the planned Soviet aircraft carriers in bad weather from American cruisers and pushed to have them built, but the Shipbuilding Commissariat balked. It refused to begin detailed design work pleading the uncertainty of the post-war building situation and the already heavy workload of its design bureaux. Undeterred the Navy continued studying cruiser designs and planned a ten-year construction programme for the period 1946–1955. This was based on defensive operations along the periphery of the Soviet Union against Anglo-American carrier groups while submarines would attack their lines of communication. Ten of these large cruisers were envisioned as part of this construction program. When the program was discussed by the Politburo on 29 September 1945 there was no great disagreement on the large cruisers, although Joseph Stalin favored increasing the size of their main guns to 305 mm (12.0 in), but did not push the issue when Admiral Kuznetsov resisted. A bigger problem was the resistance of the Shipbuilding Commissariat which said it would be impossible to lay down any ships of new design until about 1950 and that only incremental changes could be made to the designs currently in production. The Navy saw no reason why new ships, reflecting wartime experience, could not be laid down beginning in 1948. To resolve the dispute a special commission was appointed, led by Lavrentiy Beria, which mostly sided with the Shipbuilding Commissariat in that most ships of the program would be improved versions of current designs. Four of the large cruisers were to begin construction, two each at Shipyard 402 in Molotovsk and Shipyard 444 at Nikolayev with another three planned to be laid down in 1953 and 1955. This compromise was approved on 27 November 1945 and detailed design work began in 1946 for designs equipped with both the 220-mm and 305-mm guns. This was reaffirmed by a decree of the Council of Ministers on 28 January 1947. By August 1947 the Navy and the Shipbuilding Ministry had winnowed down design proposals to only three, one from each armed with 305 mm guns and a joint design armed with 220 mm guns. The latter's design was slightly smaller (2,000 tonnes (2,000 long tons)) than the Navy's 40,000 tonnes (39,000 long tons) design, and had an armor belt 50 mm (2.0 in) thinner, but was otherwise almost identical. The joint design was 2,000 tonnes (2,000 long tons) smaller with a reduced secondary armament, but was about 1.5 knots (1.7 mph; 2.8 km/h) faster. All proposals had a range of 6,000 nmi (11,110 km) at 18 knots (21 mph; 33 km/h). These designs weren't reviewed until March 1948, probably because of the need to coordinate reaction to the American Marshall Plan, and Stalin approved the Navy's more heavily protected design. But even this was subject to more delays as the detailed specifications had to be approved and this didn't occur until 31 August 1948, likely delayed by the Tito–Stalin split and the start of the Berlin Blockade, both in June. With the approval of the specifications, TsKB-17, the heavy-ship design bureau, began work on the sketch design to be submitted for approval to the Council of Ministers before the start of the technical design could begin. By March 1949 four alternatives had been completed, differing mainly in the arrangement of the 130 mm guns and the boiler layout. The bureau preferred one layout and the Navy and the Shipbuilding Ministry concurred so the bureau began the technical design, without formal approval, in order to be ready to lay down the first two ships in the third quarter of 1950 as already scheduled. However when Stalin reviewed the sketch design in September 1949 he rejected it, ordering a smaller, faster ship capable of 35 knots (40 mph; 65 km/h). TsKB-17 was able to produce a preliminary technical design that met Stalin's demands by the end of the year, an amazingly fast amount of time for what should have been a very involved process. The most likely explanation is that the designers retained as much of their original work as possible and found room for the more powerful turbines and more numerous boilers necessary to attain Stalin's specified speed by deleting the two rear twin 130 mm turrets, and their magazines, as revealed by a comparison of the 1949 and 1951 sketches. The Navy didn't like the compromises made to reduce the displacement down to Stalin's 36,000 tonnes (35,000 long tons) and to achieve the high speed demanded as revealed in a March 1950 meeting in the Kremlin where Stalin revealed critical points about his thoughts for these ships. When the admirals responded to his question about the purpose of these ships by saying that they were to fight the enemy's heavy cruisers, he contradicted them and said that their purpose was to fight light cruisers: "It is necessary to increase its speed to 35 knots and create a cruiser that will cause panic among the enemy's light cruisers, disperse and destroy them." Furthermore he believed that they would fight close to home, defending the coastal waters of Soviet Union. "You cannot blindly copy the Americans and English, they face different conditions, their ships travel far over the ocean, out of touch with their bases. We are not considering conducting oceanic battles, but instead will fight close to our own shores, so we do not need a large ammunition supply on the ship." The admirals also did not like the reduction in the secondary armament made to accommodate the larger machinery and extra boilers needed to reach the speed desired by Stalin, but he reminded them that most aircraft would attack the battlecruiser at heights below 1,500 m (4,900 ft) and the ceiling of the 130 mm was far in excess of that. He also ordered a reduction in the light anti-aircraft guns believing that its escorts would defend it. This design was approved by the Council of Ministers on 25 March 1950. This allowed the technical design process to begin and it was completed in December 1950. Reviews by the Navy and Shipbuilding Ministries in February 1951 led to some significant changes to the design in April. The original form of the bow was similar to that of the Chapayev-class cruiser light cruisers, but sea trials of the lead ship of that class in December 1950—January 1951 proved that she was very wet forward, which hindered her seakeeping ability. The Stalingrad's bow form was radically altered with a much more raked stem, its sheer and flare were greatly increased and the ship gained almost 10 m (32 ft 10 in) in length, possibly in response to the Chapayev's problems. In addition the thickness of her belt armor was increased from 150 to 180 mm (5.9 to 7.1 in), possibly in response to weight savings elsewhere. This final design was submitted for approval on 4 June 1951, but preparations for the working design drawings began before it was approved. Design General characteristics The ships of the Stalingrad class were 260 meters (853 ft 0 in) long at the waterline, and 273.6 meters (897 ft 8 in) long overall. They had a beam of 32 meters (105 ft 0 in), a maximum draft of 9.2 meters (30 ft 2 in) forward, 8.8 meters (28 ft 10 in) aft, and displaced 36,500 tonnes (35,900 long tons) at standard load and 42,300 tonnes (41,600 long tons) at full load. They were the first large Soviet-built ships with a flush deck. The hull was completely welded to save weight and they used longitudinal framing throughout. Metacentric height was estimated at 2.6 m (8 ft 6 in), presumably in the design load condition. The ships had a triple bottom underneath the armored citadel that had a height of 2.25 meters (7 ft 5 in) and 23 main watertight compartments. They had a crew of 1712 men plus space for 30 when acting as a flagship. The cost for each ship was estimated at 1.168 billion rubles, almost four times the 322 million rubles for a Sverdlov class cruiser. The ship was intended to be commanded by a rear admiral, with its executive officer, political officer and the heads of the gunnery and engineering divisions as captains 1st rank. Propulsion The high speed demanded of the ''Stalingrad''s required four TV-4 geared steam turbines, each producing 70,000 shaft horsepower (52,199 kW) and driving one propeller. They were powered by twelve water-tube boilers at a pressure of 66 kg/cm2 (6,472 kPa; 939 psi) at a temperature of 460 °C (860 °F). The machinery was arranged on the unit system so that one hit couldn't knock out all the boilers or all the turbines and immobilize the ship. Two boiler compartments, each with three boilers, were situated underneath the forward funnel, with a turbine compartment for the wing shafts immediately aft and this arrangement was repeated for the two center shafts. 5,000 tonnes (4,900 long tons) of fuel oil were carried which gave a range of 5,000 nmi (9,260 km) at 18 knots (33 km/h). Maximum speed was 35.5 knots (40.9 mph; 65.7 km/h). Eight 750 kW turbo-generators drove the 380V, 50 Hz electrical system in addition to four 1000 kW Diesel generators located outside each end of the armored citadel for a total capacity of 10,000 kW. Armor The armor scheme of the battlecruisers was quite complex with armor plates of no less than 25 different thicknesses used. Although only designed to withstand cruiser shellfire no less than 10,400 tonnes (10,200 long tons; 11,500 short tons), or 29% of the total displacement was devoted to armor. The citadel armor was intended to provide an immunity zone against 8 in (200 mm) armor-piercing shells at ranges between 13,000–15,000 yards (12,000–14,000 m) and 34,000 yards (31,000 m). The remainder of the armor was intended to resist 6-inch (150 mm) high explosive shells and 500-kilogram (1,100 lb) HE bombs. The belt armor was 180 mm (7.1 in) thick and inclined outwards at an angle of 15° to maximize its effectiveness against both plunging and horizontal fire. It had a vertical height of 5.25 m (17.2 ft), 1.7 m (5 ft 7 in) of which was below the design waterline. It covered approximately 60% of the ship's waterline or about 156 m (512 ft). 50 mm (2.0 in) of armor covered the hull side above the belt as protection from splinters. The forward end of the armored citadel was closed off by a 140-millimeter (5.5 in) thick transverse bulkhead on the forward end and 125 mm (4.9 in) aft. The deck armor in the citadel ranged in thickness, from 50 mm (2.0 in) for the upper deck, a 70-millimeter (2.8 in) middle deck—increased to 75 mm (3.0 in) over the handling rooms for the 130-millimeter (5.1 in) gun turrets—and a lower splinter deck of 15 mm (0.59 in), which increased outboard to 20 mm (0.79 in). The waterline forward of the citadel was protected by a 50-millimeter (2.0 in) splinter belt all the way to the bow, with a similar extension aft to the steering gear compartment. The middle deck behind this splinter belt was 50 mm (2.0 in) thick. The steering gear was protected by 170 mm (6.7 in) of armor on the sides, a 70–100-millimeter (2.8–3.9 in) deck and a 200-millimeter (7.9 in) armored bulkhead aft. Additional armored plates were fixed to the third bulkhead of the underwater protection system to protect against diving shells hitting below the level of the waterline belt. Their thicknesses varied depending on location and ranged oddly from 100 mm (3.9 in) amidships to 20 mm (0.79 in) over the 305 mm (12.0 in) magazines. The main battery turrets were protected by 240 mm (9.4 in) of armor on the faces and 225 mm (8.9 in) on the sides and 125 mm (4.9 in) of armor on the roofs. Their barbettes had a maximum of 235 mm (9.3 in) on their forward faces and 200 mm (7.9 in) on the after face. Below the main deck they were protected by only 195–155 mm (7.7–6.1 in) of armor. The 130 mm turrets were only protected by 25 mm (0.98 in) of armor as splinter protection. The forward conning tower had a forward face of 250 mm (9.8 in) that thinned down to 225 mm (8.9 in) on the aft section with a 100-millimeter (3.9 in) roof. Its controls and cable runs were protected by a 100-millimeter (3.9 in) tube and the lower part of the conning tower's supporting structure was protected with 20 mm (0.79 in) plates. Aft there was a lightly protected auxiliary control station with 50-millimeter (2.0 in) sides. Between the middle and lower decks the funnel uptakes were protected by 100 mm (3.9 in) of armor and 30 mm (1.2 in) between the upper and middle decks. A 125-millimeter (4.9 in) upper and 175-millimeter (6.9 in) lower grating protected the boilers from shells and fragments entering through the uptake openings. The torpedo protection system was developed on the basis of model tests and full-scale trials using a incomplete hull of the prewar Kronshtadt class battlecruiser and was expected to resist a torpedo warhead equivalent to 400–500 kg (880–1,100 lb) of TNT. It was made up of an external bulge with four longintudinal bulkheads. The first was 8–15 mm (0.31–0.59 in) thick, the second was 8–25 mm (0.31–0.98 in), the third was 50 mm (2.0 in) and the fourth 15–30 mm (0.59–1.2 in). Presumably the thinner thicknesses were at the ends of the ships where the bulkheads were squeezed together. The outer space was left empty, but the two middle spaces were filled with oil that was intended to be exchanged with sea water as it was consumed, and the inner space was also to be left empty. One curious feature was that the first and second bulkheads were concave in profile. Apparently this was believed to improve their protective qualities, although there is no indication of how it did this. "The total depth of the system was about 4–4.5 m (13–14.8 ft) amidships, which seems rather shallow." The triple bottom underneath the armored citadel was believed to protect the ship against a charge equivalent to 500 kg (1,100 lb) of TNT five meters below the ship's hull. Category:Soviet battlecruisers